GRAV-D News Archive
NGS-Norfolk Surveyor Assists with GRAV-D Measurements
Kevin Jordan, NGS’ Observations and Analysis Division, will travel from NGS Field Operations Branch in Norfolk, Virginia, to the Patuxent River Naval Air Station in Lexington Park, Maryland, to perform a component spatial relationship survey on the Gravity for the Redefinition of the American Vertical Datum (GRAV-D) aircraft. NGS’ GRAV-D project will fly over Maine and New Hampshire aboard a Navy King Air C-12 aircraft June through August. Once the instrument suite is installed, the GPS antenna must be precisely positioned relative to the other instruments on the aircraft. The spatial relationship survey will use the Topcon GPT-3002LW Theodolite and a mini prism system to measure the “X,” “Y,” and “Z” values, after the plane is leveled using jacks. Installation will occur the week of June 4, and the airborne survey is slated to begin on June 11 from Bangor, Maine. For more information, contact Vicki Childers vicki.childers@noaa.gov
The GRAV-D Survey over Lake Superior Underway
NGS had contracted with Fugro to provide airborne services and operators for a two-month long Gravity for the Redefinition of the American Vertical Datum (GRAV-D) survey effort over Lake Superior. The recently-acquired TAGS gravity meter was installed in this aircraft for the survey. Test flights, however, indicated the meter was exhibiting high sensitivity to temperature variation within the cabin. Assuming NGS’ meter was not in good working condition, we negotiated with Fugro to lease their meter for the time required for our meter to be repaired. The Fugro TAGS unit exhibited the same behavior as the NGS meter in the aircraft, indicating both meters shared a design issue. The manufacturer redesigned the sensor and resolved the problem. The repaired sensor was re-installed the week of May 21 and validated through a test flight. Surveying resumed on May 29. The Fugro survey was expected to yield about 25 percent of this year’s airborne data collection. The sensor problems will reduce the survey coverage by up to one half, which may affect the GRAV-D annual percentage accomplished for the Government Performance and Results Act (GPRA). For more information, contact Vicki Childers vicki.childers@noaa.govNGS continues work with University of Arizona and USGS to Study Ground Water Recharge near Tucson
In late June, NOAA personnel will return to Tucson, Arizona, with the FG5 absolute gravimeter to perform part two of three joint gravity measurements with the University of Arizona-Hydrology Department, the U.S. Geological Survey's (USGS) Water Resources Division, and others. Five types of gravity meters, GPS, radar mapping, and water-well monitors are being used to characterize water infiltration into desert basin sediments and subsequent out-pumping. The study seeks to link ground deformations with water-table changes. The City of Tucson’s settleage ponds in the Avra Valley west of Tucson provide access for the controllable experiments. Part one of this study revealed a distinct gravity decline measured by various gravimeters, correlating to a lowering of the water table through ground water withdrawal. With the data from this experiment, agencies such as USGS and the Arizona Department of Water Resources will be better able to use gravity and GPS data to map ground water recharge (from precipitation or canals) and manage pumping to better budget valuable water resources. For more information, contact Daniel Winester dan.winester@noaa.gov
NGS’ Vicki Childers Presents at NASA Goddard Space Flight Center
On April 11, Dr. Vicki Childers presented an invited talk at NASA’s Goddard Space Flight Center’s “Solar System Exploration Seminar.” Vicki discussed advancements in airborne gravity science achieved by NGS’ Gravity for the Redefinition of the American Vertical Datum (GRAV-D) Project since its inception four years ago. NASA researchers that attended the talk study many properties of the Earth and other planets of the solar system, including the gravity and magnetic fields of the planets. Vicki’s presentation encouraged the continued exchange of ideas between NOAA and NASA on common topics of interest, including GRAV-D. Topics covered included the status of the GRAV-D Project, project achievements in high-accuracy airborne gravity data and GPS processing, validation of data versus global models, and continuing research. GRAV-D will create a new vertical reference system that will improve floodplain mapping and help mitigate risks for coastal communities from tsunamis, hurricanes, and storm surges. When complete, the improved elevations from GRAV-D products will provide an estimated $4.8 Billion in cost savings to the nation. For more information, contact Vicki Childers vicki.childers@noaa.gov
GRAV-D Completes Release of Gulf Coast Airborne Gravity Data for Public Use
Airborne gravity data covering most of the U.S. Gulf Coast from the Mexico border to Alabama is now available on NGS’ Gravity for the Redefinition of the American Vertical Datum (GRAV-D) website. This is a milestone for the program which is designed to produce high-accuracy airborne gravity data to contribute to a new vertical reference frame accurate at the 2 cm level (where possible). NGS’ recently validated Texas data confirms that the addition of airborne gravity data to NGS models provides significant improvements. Further validation is being completed by Texas A&M (Corpus Christi), the University of Houston, and the National Geospatial-Intelligence Agency. For more information, contact Theresa Diehl theresa.diehl@noaa.gov
U.S. and Canada Agree to Joint North American Height
NOAA’s National Geodetic Survey (NGS) and Natural Resources Canada (NRC) have agreed, in writing, to developing a common vertical reference system in North America and what the definition of “zero height” will be for the new system. This new vertical reference system will be based on a gravity model, or geoid, which will allow GPS to measure heights relative to sea level more accurately than ever before. Canada will be adopting its new gravity-based vertical reference system in FY2013, while U.S. development to even higher accuracy standards will occur in 2022 after completion of the NOAA Gravity for the Redefinition of the American Vertical Datum (GRAV-D) initiative. In issuing these statements, both agencies have agreed to a commonly defined vertical reference system for all of North America, with the further goal of a joint continent-wide adoption of one system by 2022. Agreeing to a common reference system will facilitate data sharing and consistency across borders between the two countries. A common “starting point,” or zero height level, for the system will also allow elevations to be standardized seamlessly across borders. For more information, contact Dru Smith dru.smith@noaa.gov
NGS Hosts ASPRS Annual Meeting Discussion Group
NGS will be hosting a one-hour Hot Topic discussion group at the American Society for Photogrammetry and Remote Sensing (ASPRS) Annual Meeting held in Sacramento, California the week of March 19. NGS’ topic, “Modernization Program of the North American Reference Frame,” will include a presentation and discussion by Mike Aslaksen, Vicki Childers, and Chris Parrish. The presentation will provide an opportunity to apprise the ASPRS community of NGS’ plans for modernization of both the geometric and geopotential datums and the status and progress of NGS’ Gravity for the Redefinition of the American Vertical Datum (GRAV-D) Project. The audience will want to know how the new datums will affect their production and the status of data contracting for the GRAV-D project. For more information, contact Vicki Childers vicki.childers@noaa.gov
NGS Joins USGS and University of Arizona Study of Aquifer Recharge
A monitoring experiment sponsored by the U.S. Geological Survey (USGS); the University of Arizona, Tucson; and others occurred the week of March 5 using two cryogenic, superconducting gravimeters (one portable, one stationary), portable relative gravimeters, absolute gravimeters (A-10 and FG5) and tidal gravimeters. The City of Tucson, Arizona, takes water from the Colorado River (via canal) and stores it in underground aquifers. Within the aquifer, the Colorado River water’s chemistry changes as it mixes with the other stored water to become less reactive with the old city water pipes. The water is stored in the Avra valley just west of Tucson and is poured into man-made ponds and allowed to settle into the local aquifer. Modern gravity meters can detect this change in mass, both as water moves into the aquifer and later as it is pumped out. For more information, contact Dan Winester dan.winester@noaa.gov
NGS’ GRAV-D Field Team Hosts Visitors
NGS’ Gravity for the Redefinition of the American Vertical Datum (GRAV-D) field team—currently located in Fort Wayne, IN and flying over the Lake Michigan area—hosted a number of visitors recently to continue to improve operations and explore future opportunities. Representatives from Micro-g LaCoste, the company that manufactures the gravimeter used by the GRAV-D Project, visited with the latest version of a gravimeter in order to test data collection against NGS’ current meter. The new version is small and light and can be used in unmanned aircraft missions. In addition, Micro-g is assisting with field tests of the second TAGS meter, recently acquired by the GRAV-D team. Vicki Childers, GRAV-D Project Manager, joined the field team for Micro-G’s visit. Monica Youngman also visited the GRAV-D field team and worked with the field team, Justin Dahlberg and Greg Watson, for about four days to learn field operations and facilitate communications between the field team and office staff. For more information, contact Vicki Childers vicki.childers@noaa.gov
NGS Hosts ASPRS Annual Meeting Discussion Group
The National Geodetic Survey (NGS) hosted a Hot Topic discussion group at the American Society for Photogrammetry and Remote Sensing (ASPRS) Annual Meeting in Sacramento, California the week of March 19. NGS’ topic, “Modernization Program of the North American Reference Frame,” included a presentation and discussion by NGS staff. The presentation provided an opportunity to apprise the ASPRS community of NGS’ plans for modernization of both the geometric and geopotential datums and the status and progress of NGS’ Gravity for the Redefinition of the American Vertical Datum (GRAV-D) Project. For more information, contactVicki Childers vicki.childers@noaa.gov
GRAV-D Project Completes Survey in Indiana
The National Geodetic Survey’s (NGS) Gravity for the Redefinition of the American Vertical Datum (GRAV-D) Project completed its airborne survey out of Ft. Wayne, Indiana, on March 26. The project had been working on the Bureau of Land Management’s Pilatus PC-12, on loan from the Alaska Fire Service in Fairbanks. This most recent survey effort completes approximately five months of work aboard this aircraft since September 2011 in both Ft. Wayne and San Antonio, Texas. The next survey will be aboard a Fugro aircraft working out of Duluth, Minnesota, beginning May 1. The Minnesota survey will last two months and will cover the Lake Superior region. For more information, contact Vicki Childers vicki.childers@noaa.gov
GRAV-D Airborne Surveying Status
NGS’ Gravity for the Redefinition of the American Vertical Datum (GRAV-D) Project has resumed airborne gravity surveys over San Antonio, Texas. Data gathered will be combined with the recent data collection from NGS’ Geoid Slope Validation Survey in Texas this past summer. For more information, contact Vicki Childers vicki.childers@noaa.gov
NGS’ Geoid Slope Validation Survey Resumes in Texas
Gravity measurement resumed along the Geoid Slope Validation Survey line in January, with NGS Observation and Analysis Division personnel making absolute gravity and gravity gradient measurements along the line. NGS’ Gravity for the Redefinition of the American Vertical Datum (GRAV-D) personnel are assisting in the measurement, while the Pilatus aircraft is in maintenance. The remaining measurements will require two to three more months to complete. For more information, contact Vicki Childers vicki.childers@noaa.gov
NGS’ GRAV-D Survey Tests New Systems in San Antonio
NGS’ Gravity for the Redefinition of the American Vertical Datum (GRAV-D) survey got underway the week of January 9 in San Antonio, Texas and will continue over the next few weeks. GRAV-D continues to partner with the Bureau of Land Management to work aboard their Pilatus PC-12 aircraft. The survey extends the existing Texas work westward and into Mexico. In addition to its usual GRAV-D surveying duties, the large aircraft will be a test platform for newly-acquired equipment, allowing a second gravimeter to collect data simultaneously alongside the proven GRAV-D gravimeter. In addition, the GRAV-D team will conduct the first airborne testing of a new, experimental gravimeter designed for work on unmanned aircraft systems (UAS). For more information, contact Vicki Childers theresa.diehl@noaa.gov
NGS’ GRAV-D Project Releases Airborne Gravity Data Collected over the South and Central Texas Coastline
NGS’ Gravity for the Redefinition of the American Vertical Datum (GRAV-D) Project has recently released new airborne gravity data to the public. The released GRAV-D data block contains airborne gravity lines collected during a survey from March through May, 2009, aboard the NOAA Cessna Citation II aircraft that covered a 300-km by 600-km area of the south and central Texas Gulf coast. Nearby blocks of data in eastern Texas and in Louisiana will become publicly available in February 2012.With data flowing to the NGS geoid team, work can begin in earnest in preparing the combined gravity field needed for geoid creation. Orthometric heights based on gravity may be used to accurately predict water-flow patterns, land slide/slump risk, and other factors affected by Earth’s gravity field. Currently, GPS provides only ellipsoidal heights, but a new GRAV-D-derived datum will facilitate rapid access to orthometric heights.
GRAV-D is NGS’ ambitious project designed to provide airborne gravity data which, when combined with satellite and surface gravity measurements, will enable the creation of a gravimetric geoid. The geoid provided by GRAV-D will create a new vertical datum, accurate to 2 centimeters (in non-mountainous regions) by 2022. For more information, contact Theresa Diehl
theresa.diehl@noaa.gov
NGS Acquires New Equipment to Improve Productivity in GRAV-D Airborne Data Collection
The week of December 12, NGS took delivery of a new NovAtel SPAN GPS/IMU Inertial System. The SPAN system “tightly couples” the GPS with a robust Honeywell MicroIRS IMU to provide improved position, velocity, and acceleration information, as well as angular attitude, for aircraft used in NGS’ Gravity for the Redefinition of the American Vertical Datum (GRAV-D) Project. GRAV-D’s gravity data-processing will benefit from these blended GPS/IMU solutions, as well as the pitch, roll, and yaw attitude data. The acquisition of this system completes the second airborne suite of airborne instrumentation. Two instrument suites allow for two teams to be working at the same time, which will aid in NGS’ ability to accomplish our metrics in terms of percentage of the total area flown annually. January 2012 will be a testing phase for both the new IMU and new TAGS meter acquired in a few weeks, as we will fly the new and the old sensors in combination. For more information, contact Vicki Childers vicki.childers@noaa.gov
NGS Releases Initial Gravimetric Geoid Validation Results
In partnership with international colleagues and state, local, and university partners, NOAA validated an important component of the latest gravity surface model (the “geoid”) in 2011 and presented initial survey results at the December American Geophyiscal Union Conference in San Francisco. Tests performed over an approximate three-month period resulted in a comprehensive survey along a 300-km route from Corpus Christi to Austin, Texas. Through various measurements, the survey validated significant improvements in elevation measurements that will be available to users as part of NOAA’s Gravity for the Redefinition of the American Vertical Datum (GRAV-D) initiative. For more information, contact Dru Smith dru.smith@noaa.gov
NGS’ Daniel Winester Visits National Geospatial-Intelligence Agency (NGA) for Gravity Data Processing
NGS has been conducting the Texas Geoid Slope Validation Survey (GSVS) for several months as a method to help validate the quality of the geoids (reference surfaces) NGS produces. The GSVS has involved a number of measurements made along a line that extends from Austin to Corpus Christi, TX, including both relative and absolute gravity measurements. Our colleagues at the National Geospatial-Intelligence Agency (NGA) have hosted NGS geodesist, Daniel Winester, at their facility in St. Louis, Missouri, and assisted him in processing the relative gravity measurements. This meeting is a follow-up to a meeting two years ago where NGA shared their processing software with NGS and provided training on its use. NGS expects the software will become a regular part of the NGS gravity processing strategy. For more information contact Vicki Childers. vicki.childers@noaa.gov
NOAA Performs Airborne Gravity Survey of Lakes Michigan and Erie
NGS’s Gravity for the Redefinition of the American Vertical Datum (GRAV-D) Project resumes airborne gravity data collection in the Great Lakes this week. The new survey extends approximately 150 km into Canada and will complement the survey recently completed over Lake Ontario and the northern section of Lake Erie aboard the Fugro aircraft. Once this survey is complete, about two-thirds of the Great Lakes area will have been surveyed. These surveys provide critical and timely gravity data to support the development of the upcoming International Great Lakes Datum of 2015 (IGLD15). For more information contact Vicki Childers vicki.childers@noaa.gov
NOAA’s Gravity Survey Data Released to the Public
The week of September 5, NOAA announced the first public release of airborne gravity data as part of NOAA’s Gravity for the Redefinition of the American Vertical Datum (GRAV-D) Project. The released data block contains airborne gravity lines collected during the Alabama 2008 survey flown from Montgomery, AL in January and February, 2008 aboard the NOAA Cessna Citation II aircraft. The data block covers a 100 km x 400 km area of the Gulf of Mexico and a small portion of coastline. This data release also marks the roll-out of a new GRAV-D data web-portal, with a GoogleMap interface to allow easier browsing of data that are in all stages of planning, collection, processing, and public release. The GRAV-D data may be downloaded via the “Data Products” link on the GRAV-D web site: http://www.ngs.noaa.gov/GRAV-D/data_products.shtml. For more information, contact Theresa Diehl theresa.diehl@noaa.gov
September 14, 2011 Marks the One Billionth Second Since the Start of GPS Time
The Global Positioning System time is the atomic time scale implemented by the atomic clocks in the GPS ground control stations and the GPS satellites. GPS time was zero at 0-hour, January 6, 1980, and on September 14, 2011 at 01:46:40, 1 billion seconds will have passed since the start of GPS time. For more information contact Neil Weston Neil.D.Weston@noaa.gov neil.weston@noaa.gov
NOAA’s GRAV-D Program to Begin Collecting Gravity in the Great Lakes
NOAA’s Gravity for the Redefinition of the American Vertical Datum (GRAV-D) project is working with contracting company, Fugro Airborne Surveys Corp., to begin an airborne gravity survey in the eastern Great Lakes. Fugro is providing aircraft and data acquisition support as a stepping stone to future data-collection contracting. Operations will begin around August 8th out of Buffalo, NY and continue for about four weeks. This gravity data will be critical for updating the International Great Lakes Datum (IGLD), which is essential to provide accurate geodetic and water-level products and services to the Great Lakes community. For more information, contact Vicki Childers vicki.childers@noaa.gov
NGS Rolls Out the Latest Work to International
NGS representatives rolled out the latest work on the Gravity for the Redefinition of the American Vertical Datum (GRAV-D) Project to the international community at the 25th General Assembly of the International Union of Geodesy and Geophysics (IUGG) quadrennial meeting in Melbourne, Australia June 27 to July 8. GRAV-D is an ambitious effort to move towards a unified height reference system for all of North America. In addition to making announcements about GRAV-D, NGS engaged in meetings to discuss international efforts to adopt a world height system. For more information, contact Dru Smith dru.smith@noaa.gov
NGS’ Theresa Diehl to Attend Glacial Isostatic Adjustment Training in Sweden
NGS scientist, Dr. Theresa Diehl, is attending a week-long training on glacial isostatic adjustment (GIA) from June 13 to 17, in Gavle, Sweden. GIA is the process governing how the solid earth rebounds/subsides after the melting of a large ice mass. For example, there is ongoing significant vertical ground movement in Canada and the northeastern United States. The massive Laurentide ice sheet from the last ice age approximately 20,000 years ago covered this region and depressed the land, and the land is still rebounding after the melting of the ice sheet. The training course will focus on modeling and understanding ice sheet mass changes, the solid earth response, and related sea level variations. Understanding the effects of vertical ground adjustments from GIA is important for predicting future changes in ground height in Alaska and the northeastern United States. Tracking temporal changes to the vertical datum over time is the goal of the long-term monitoring portion of NGS’ Gravity for the Redefinition of the American Vertical Datum (GRAV-D) Project. For more information, contact Theresa Diehl theresa.diehl@noaa.gov
NGS GRAV-D Airborne Survey Concludes in Alaska
NGS’ Gravity for the Redefinition of the American Vertical Datum (GRAV-D) airborne survey has wrapped up operations out of Fairbanks, AK. The survey was conducted aboard a NOAA WP-3 Hurricane Hunter. The extended endurance, with more than 150 hours flown, allowed for new data collection over the Arctic Ocean and the northern Alaska coast. For more information, contact Vicki Childers vicki.childers@noaa.gov
NGS’ Dan Winester Presents at EarthScope Conference
NGS’ Dan Winester will be attending the EarthScope Conference in Austin, Texas from May 17-20. EarthScope hosts the Plate Boundary Observatory (PBO), a large contributor to the Continuously Operating Reference Stations (CORS) network. EarthScope also performs seismic monitoring and seismographic tomography of the Earth’s interior. Dan will present a poster on density modeling of the surface rocks of the United States; part of NGS’ Gravity for the Redefinition of the American Vertical Datum (GRAV-D) Project, as well as attend workshops on computer modeling of geology and ideas for undergraduate geodesy curriculum in universities. For more information, contact Dan Winester daniel.winester@noaa.gov
NGS Presents Widely Attended Webinar on GRAV-D Project
National Geodetic Survey’s Dr. Theresa Diehl presented a free webinar on May 9 with about 100 attendees from across the country and from various organizations, including federal, state, university, and surveying/environmental corporations. In the webinar titled An Update on the Gravity for the Redefinition of the American Datum (GRAV-D) Project, Diehl discussed the current vertical datum used on federal maps and why NGS’ GRAV-D Project was instated to create a new, 2 cm-accurate datum. Diehl also presented an update on how much the GRAV-D program has accomplished to date, what is planned for the next decade, and how NGS stakeholders will be able to use the new datum when it is available after 2022. The presentation and slide program was recorded and will soon be available to the public on the Corbin Training Center website. For more information contact Theresa Diehl Theresa.Diehl@noaa.gov.
Community Surveyors to Experience Significance of NOAA GRAV-D Airborne Operation
On February 5, the National Geodetic Survey (NGS) California State Geodetic Advisor, Marti Ikehara, brought 22 surveyors from the local community to view NGS Gravity for the Redefinition of the American Vertical Datum (GRAV-D) airborne operation at McClellan Field in Sacramento, CA. The guests were given an opportunity to observe how an airborne gravity survey is conducted by viewing the instrumentation on board the aircraft to gain an understanding of how NGS operates its GPS base stations. Airborne operators escorted the surveyors and answered their questions. For more information, contact Vicki Childers.
NOAA National Geodetic Survey Acquires New Absolute Gravity Meter for Increased Effectiveness and Efficiency of Gravity Readings
NOAA National Geodetic Survey (NGS) has acquired a new A10 absolute gravity meter for terrestrial survey work that will be used to establish gravity ties for airborne gravity surveys. NGS took possession of the meter and personnel received training in its operation at the end of January at Micro-g LaCoste, the instrument's manufacturer in Lafayette, Colorado. The new meter will increase the efficiency and cost effectiveness of NGS gravity surveys with its ease of use, durability, and shorter observation period (4 vs 24 hrs for the FG-5). The new meter will be placed into service by late February in support of GRAV-D airborne operations. For more information, contact Vicki Childers.
NOAA National Geodetic Survey Adds a Second Pilot to its GRAV-D Sacramento Airborne Survey to Boost Survey Coverage
On February 1, a second pilot was added to NOAA National Geodetic Survey Gravity for the Redefinition of the American Vertical Datum (GRAV-D) operation in the Sacramento, California survey. The survey is being flown aboard a Department of the Interior, Bureau of Land Management Pilatus PC-12 aircraft which can be operated with a single pilot. The two- pilot operation will continue through the end of this survey on February 24. The PC-12 aircraft has excellent endurance and can cover a significant area in a given flight. For more information, contact Vicki Childers.
NOAA to Highlight GRAV-D at American Geophysical Union Annual Fall Meeting
NOAA National Geodetic Survey (NGS) will present at the American Geophysical Unions (AGU) Annual Fall Meeting in San Francisco, CA from December 13 to 17. NGS contributions at the AGU conference include analysis and information regarding NGS gravity collection activities and their applications. NGS will also provide sessions on its Gravity for the Redefinition of the American Vertical Datum (GRAV-D) Project initiative and related work. For more information, contact Vicki Childers
GRAV-D Alaska Survey Operations to Conclude for the Season in Anchorage, AK
NGS Gravity for the Redefinition of the American Vertical Datum (GRAV-D) airborne team transitioned to Anchorage, AK from Fairbanks for its final week (ending November 15) for the 2010 calendar year. The Department of the Interiors Bureau of Land Management aircraft employed by the team was in scheduled maintenance in Anchorage, and by moving operations to Anchorage, NGS was able to capitalize on additional flight days. After New Years, the GRAV-D team will continue operations in January and February from McClellan Field in Sacramento, CA with survey work in central and northern California until Alaska warms up sufficiently to resume the GRAV-D airborne effort there. For more information, contact Vicki Childers
NGS Sandra Preaux is Awarded NOAA Team Member of the Month
Congratulations to Sandy Preaux upon her selection as NOAA Team Member of the Month! Sandy is an airborne gravity scientist with NGS Gravity for the Redefinition of the American Vertical Datum (GRAV-D) Project, and she is being honored for her many contributions to the team. Sandy's terrific attitude, work ethic, and high levels of productivity have been an inspiration to the GRAV-D team. NGS is very pleased and proud to see Sandy receive this award! For more information, contact Vicki Childers
Vicki Childers to Present at National Digital Orthoimagery Program
Vicki Childers, NGS Gravity for the Redefinition of the American Vertical Datum (GRAV-D) Project Manager, has been requested by the National Digital Ortho Photo (NDOP) group to provide a 20-minute presentation on GRAV-D at their upcoming meeting in Pascagoula, MS on November 17. Vicki will give participants an overview of GRAV-D, as well as a review of FY10 GRAV-D projects and plans for FY11. The NDOP group has particular interest in the Projects work in Alaska. The members of NDOP consist of representatives from almost all federal agencies that coordinate ortho-imagery purchases, as well as representatives from the National States Geographic Information Council (NSGIC). Due to FY11 travel limitations, Vicki will present her talk via Web-Ex. For more information, contact Vicki Childers
NOAA Hosts North American Comparison of Absolute Gravimeters
NOAA National Geodetic Survey (NGS) will host the North American Comparison of
Absolute Gravimeters (NACAG-2010) from October 18 to 22 at NGS Table Mountain
Geophysical Observatory (TMGO) in Longmont, CO. Other U.S. federal agencies, as well as
other government agencies from Canada, will participate, with tentative plans including nine
absolute gravimeters for the comparison.
Regular comparisons between the few absolute gravimeters in the world is necessary to validate
the achievable accuracy of each meter relative to the group mean. This information can be used
in standardizing gravity surveys internationally. A report of the comparative offsets of all
absolute gravimeters operating in North America will be presented both online and to the
International Association of Geodesy. NGS intends to use absolute gravity measurements to
help monitor long-term change to the new vertical datum as part of its Gravity for the
Redefinition of the American Vertical Datum (GRAV-D) Project. NGS has invested significant
time and money into transforming the TMGO into a world-class gravity observatory, elevating
NGS status in the international absolute gravimeter community.
Contact person (provide name, email, and phone including area code and extension):
Dru Smith Dru.Smith@noaa.gov
National Research Council to Publish Report on Geodetic Infrastructure for the Nation
The National Academies of Sciences, National Research Council (NRC) is publishing a report titled Precise Geodetic Infrastructure: National Requirements for a Shared Resource. The report was requested jointly by NASA, the U.S. Naval Observatory, U.S. Geological Survey, National Geospatial Intelligence Agency, National Science Foundation, and NOAAs National Geodetic Survey (NGS). According to the report, renewed investment in the Nations geodetic infrastructure is needed to maintain and modernize existing systems and to enable the development of sophisticated new applications to provide significant economic, national security, and scientific benefits. This report recommends renewed investment in several NOAA programs, including NGS-led initiatives that are already underway, such as the National Height Modernization Program, the Gravity for the Redefinition of the American Vertical Datum (GRAV-D) airborne gravity collection project, the Continuously Operating Reference Station (CORS) Network, and the installation of foundation CORS stations.
For more information, view a summary of the report.
NGS Welcomes Chi-Hsun (Chris) Huang, Visiting Scientist from Taiwan
Chi-Hsun (Chris) Huang is visiting and working with NOAAs National Geodetic Survey (NGS) for six months, beginning the week of July 19. Chris will exchange ideas and techniques related to reducing gravity data into geoid-height models. A Ph.D. student of Dr. Cheinway Hwang at the National Chiao Tung University in Taiwan, Chris experience in collection and reduction of airborne and shipborne gravity data to geoid models is similar to the aims for collection in NGS' Gravity for the Redefinition of the American Vertical Datum (GRAV-D) program. Chris will spend his time in the United States learning about our programs and techniques and exploring how his suite of programs may be integrated into the GRAV-D program.
NGS Welcomes Ali Turkezer, Visiting Scientist from Turkey
NOAAs National Geodetic Survey (NGS) welcomed Ali Turkezer, on a two-week visit from his native Turkey. Turkey is particularly interested in NGS Height Modernization and Gravity for the Redefinition of the American Vertical Datum (GRAV-D) programs. Turkey encounters similar issues to the United States in maintaining their benchmarks and height systems, and Ali is eager to see how we have resolved several of these issues. In turn, Ali plans to present information on the approach taken by Turkey.
NGS Contributes to International Collaborative Effort in the Unification of Height Systems
During the week of August 8-13, staff from the National Geodetic Survey (NGS) will participate in the American Geophysical Union (AGU) Meeting of the Americas, in Iguau Falls, Brazil. NGS will present posters on the inter-comparison between future height systems in North and South America to ensure continuity in the overlapping geographical areas of the Caribbean, the Gulf of Mexico, and Central America. NGS will also present its work with airborne gravity data collected as a part of its Gravity for the Redefinition of the America Vertical Datum Project (GRAV-D) to better strengthen the relationship between satellite missions (GRACE, GOCE) and terrestrial gravity data.
See 2010 The Meeting of the Americas.
NOAA Begins Preparation for Gravity Surveys in Alaska
On May 17, staff from the Gravity for the Redefinition of the American Vertical Datum (GRAVD)
team of NOAAs National Geodetic Survey will travel to Minneapolis, MN to install
equipment for the summer 2010 GRAV-D airborne gravity survey mission in Alaska. The
summer survey will be conducted from Anchorage and Kodiak aboard the NOAA turbo
commander, an aircraft used most of the year to conduct aerial snow survey operations.
This next phase of the GRAV-D survey in Alaska will begin the last week of May and continue
through the end of August, with 300 flight hours planned. The survey will cover the
southwestern coastal regions of the state, filling in the region not covered by the 2008 and 2009
surveys.
NOAA Collaborates With Other Federal Agencies on Airborne Gravity Survey in Western Alaska
August 2009- NOAA's National Geodetic Survey completed a Gravity for the Redefinition of the American Vertical Datum (GRAV-D) airborne survey in western interior Alaska on August 11th, with portions of western interior Alaska area flown. This survey represents a landmark in the GRAV-D initiative, due to the collaboration with two other federal agencies, the Naval Research Lab (NRL) and the US Geological Survey (USGS). The most recent survey work was flown aboard an NRL King Air C-12 aircraft and was the first GRAV-D airborne survey flown on aircraft not belonging to NOAA. NRL proved to be an able partner, and the survey went well. USGS participated in the survey by providing a magnetometer, as well as additional funding to support flights for calibrating the instrument. More collaborative partnering efforts are expected with both agencies in the future.
This collaboration with the US Navy represents another example of how NOAA and other federal agencies are working together to meet common goals, as outlined in Dr. Lubchenco's announcement of July 24, 2009.
See Dr. Lubchenco's NOAA World story.
Socio-Economic Benefits of GRAV-D estimated at $522 Million Annually
June 2009- Leveson Consulting has evaluated the benefits to the US economy provided by NOAA-NGS' National Spatial Reference System, including CORS and GRAV-D. The report was unveiled at a briefing on Capitol Hill and is available online: one-pager and full report. The expected value of GRAV-D (half of which is due to projected improvements in flood plain mapping) is $522 Million dollars annually. The total value of the National Spatial Reference system, without the improvement of the vertical datum through GRAV-D, already exceeds $2.4 Billion annually. Additional information is available from the National Ocean Service and a podcast.
Western and Northern Gulf Coast Survey Completed
May 2009- A massive GRAV-D effort to survey the Gulf coast from the Texas/Mexico border to the Alabama/Mississippi border, partially funded by the Army Corps of Engineers, was completed in mid-May 2009. The multi-part survey was started in October 2008 in response to the need of the Army Corps for future storm preparedness and, thus, a better vertical datum in the Gulf.
University of Texas at Austin Students Experience GRAV-D Operations
March 2009- The GRAV-D team hosted a group of undergraduate students from a geophysics class at the University of Texas (UT) at Austin on the 10th. The students learned about gravity fundamentals and were able to examine the actual GRAV-D instrumentation, while the team and plane were in Austin for the western Gulf of Mexico survey. The students were first given a short informational talk by GRAV-D scientist Dr. Diehl about airborne gravity fundamentals, herself a graduate of the UT geophysics Ph.D. program. GRAV-D Project Manager Dr. Childers then led the students out onto the airport tarmac to examine the GPS stations used in survey operations and Dr. Diehl led them through a tour of the Cessna Citation to examine and discuss the operation of the airborne instrumentation. The experience was enjoyed by all!
GRAV-D Completes Survey of Puerto Rico and the Virgin Islands
January 2009- Flying ~100 hours over the course of nearly 4 weeks, the GRAV-D team has completed both a high-altitude survey (measuring 400 km x 500 km) at 35,000 ft over Puerto Rico and the Virgin Islands, as well a small low-altitude survey nominally at 5,000 ft over the Virgin Islands. The survey was a huge success.
Two New Hires for GRAV-D
January 2009- The program acquired two new team members this month. Dr. Theresa Diehl joined the Silver Spring, MD office as a specialist in airborne gravity data collection and processing. Dr. Diehl completed her Ph.D. at the University of Texas at Austin in August in geophysics, focusing on airborne gravity studies of Antarctic sub-ice geology and tectonics. David Schmerge joined the Table Mountain Gravity Observatory in Boulder, CO with a background in absolute gravimeter operations and water resource monitoring. Schmerge has previously worked for the U.S. Geological Survey and the Arizona Department of Water Resources.
GRAV-D Scientists Attend Annual Geophysics Meeting
December 2008- NGS geodesists put in a strong showing at the American Geophysical Union Annual Fall Meeting in San Francisco, CA. They chaired a session on improving vertical datums through the use of gravity data and made six scientific presentations.
Table Mountain Gravity Observatory Renovations Begin
September 2008- The NGS Observatory for absolute gravimetry at Table Mountain, CO (outside Boulder) has begun renovations of their facility.
GRAV-D Test Survey Completed Around Anchorage, Alaska
July 4-31- The month of July was a busy one for GRAV-D! In an effort to support "Hydropalooza" (the Integrated Ocean and Coastal Mapping (IOCM) initiative in the Kechamak Bay region of Alaska), the National Geodetic Survey took the airborne gravimeter to Anchorage Alaska and flew almost 100 hours, covering a region 400 by 500 km (see plot). This new gravity data will allow NGS to compute a more accurate gravimetric geoid for this region than has ever been done before. This geoid will support VDatum, IOCM and the GRAV-D project.
GRAV-D Project Manager Hired
May 27th- NGS has hired Dr. Vicki Childers as the GRAV-D Project Manager. Dr. Childers joins NOAA after 12 years at the Naval Research Laboratory where she worked as a geophysicist conducting airborne gravity surveys campaigns.
NGS Flies GRAV-D Test Flights in Northern Gulf of Mexico
January 19-Februrary 15- Members of the GRAV-D airborne and terrestrial teams worked together with scientists from Micro-G LaCoste to install and operate NGS' TAGS airborne gravimeter in the northern Gulf of Mexico.
NGS Trains Airborne Gravimeter Operators with Ground Tests
November 15-17- In planning for initial flights in 2008, NGS has trained three preliminary instrument operators, with the help of Micro-G, on the operation of the TAGS unit, and the initial field processing of data from it. In fashion similar to how it was first lab tested at Micro-G , the TAGS unit was mounted in a road vehicle, simulating airplane operation without the cost of actually flying a plane. The training was a success in both dissemintation of operational training as well as highlighting technical difficulties and arriving at solutions to them.
NGS Approves Final Version of GRAV-D Plan
November 14- At a meeting of the NGS Executive Steering Committee, the GRAV-D plan was approved for public release. A final, edited version was made available in PDF form on December 7, 2007. The plan is available for download as a (.pdf) here.
NGS Acquires Airborne Gravimeter
October 25- As part of its dedication to re-defining the vertical datum through a gravimetric geoid, NGS acquired a new Turnkey Airborne Gravity System (TAGS) from the Micro-G/LaCoste company. This new system combines the latest in airborne gravimeter technology with innovative user-friendly operational software and training in the use of both. On October 25th, the new gravimeter was delivered to NGS. Nigel Brady of Micro-G LaCoste came along to teach NGS personnel how to pack and unpack the meter from its delivery crates and give a quick demonstration of the basic operation of the meter (in static mode). Photos from the delivery will be available soon.
NGS Holds Gravity Seminar at Corbin
April 10-11- A small contingent of NGS personnel converged on the Corbin, Virginia facility to share information with one another on various aspects of NGS's involvement in gravity, geoid modeling, heights and vertical datums. Attendees included instrument operators, research scientists, policy experts, programmers and other personnel who all have some connection to gravity, geoid or height issues. Dan Winester began with a demonstration on the set-up and operation of the FG-5 Absolute Gravimeter (see slideshow to the right). Lectures were held over two days by Dan Winester, Dan Roman and Dru Smith, helping to disseminate a combination of field operational issues, gravity and geoid research and future plans to the attendees. Tim Niebauer, President of Micro-G/LaCoste attended to educate NGS as to the latest gravity equipment (terrestrial and airborne) and services his company offers. Photos from the seminar will be available soon.
NGS Releases Draft of 10 Year Plan
February 12- The NGS Executive Steering Committee approved the public release of the NGS 10 year plan. That document was the first official announcement by NGS of its intention to re-define the vertical datum of the United States through the combination of GNSS technology combined with a gravimetric geoid model. The 10 year plan can be downloaded in (.pdf) format here. Following that release, work was begun on an official gravity survey plan to support this decision. Eventually, that plan came to be known as "GRAV-D".
